The present invention relates to an apparatus for optoelectronically determining power for a moving machine element and more particularly, relates to an apparatus for measuring torque and rotational speed of the moving machine element simultaneously and in a simplistic yet effective manner.
The derived physical torque (M) is defined as the product of the force (F) and the vertical distance of its line of application (lever arm) from the center of rotation, and is a significant measure of the loading on a drive. In many cases, recording of the torque is sufficient for monitoring and controlling rotary motion. However, the derived physical principle or fundamental quantity of mechanics is power (P). This is defined as the product of rotational speed and torque.
Power recording is indispensable for the complete characterization of a drive. By way of example, the quantities power and rotational speed are always specified for designing a motor. If two quantities are cited, the third variable can be calculated. The resultant maximum torque of a motor is calculated from the equation M=P/n, where n is the number of revolutions within one unit of time.
One example which may be taken is a stirring mechanism whose mixer rod is equipped with an apparatus for determining torque in accordance with DE patent 198 49 225, which is herein incorporated by reference in its entirety. The firmer the liquid mass to be stirred becomes, the higher the torque bearing on the mixer rod becomes. Thus, the torque measured is a measure of the viscosity of the substance to be stirred. When the torque reaches a prescribed value, processing of the material is terminated and further processes can be started automatically.
If the quantity rotational speed is additionally recorded, a statement can be made about the power which is to be applied. Statements can be made about the choice of the motor and the design of the drive components. In general, there is always interplay between the three quantities power (P), torque (M) and rotational speed (n). Provided that a motor always applies its maximum constant power, an increase in the torque always results in a reduction in the rotational speed, which can easily be seen from the relationship P=Mxc3x97n.
Thus, it would be desirable to provide a simple apparatus which can effectively determine the torque and rotational speed of the moving machine element, e.g., a rotating machine element.
The present invention is based on the object of providing an apparatus which permits the two quantities which can be recorded on the machine element, namely torque and rotational speed, to be determined in a technically simple manner. The apparatus includes two parallel coding discs which are mounted on the machine element and each have grid lines or light windows distributed over their circumference. The application has a light source which is arranged on one side of the coding discs and an associated light meter is arranged on the opposite side of the discs. The light source and the light meter have an annular design in order to transilluminate all the light windows to a largely uniform degree, and a diffusion disc is arranged in a beam path between the light source and the coding discs.
According to the present invention, the object is achieved as a result of a light barrier being mounted outside the region of the light windows on the coding discs and at least one light window on one of the coding discs being formed in a beam path of the light barrier. In addition, a translucent, endless strip is formed on the other of the parallel coding discs.
The recording of the rotational speed is independent of the torsion, and hence of the torque determination, and is determined by the rotation. The optronic components light-emitting diode and photodiode are mounted directly in front of the discs. During operation, the user is provided with both a torque voltage signal and a rotational speed pulsed signal. To calculate the power, the rotational speed needs to be calculated from the rotation signal and multiplied by the measured torque. There are many items of measuring equipment which measure the quantities torque and rotational speed simultaneously. However, no measuring equipment is known in which the combination of the aforementioned measurement principles are implemented with the same level of technical simplicity. The present invention provides such an apparatus.